1	Perianth in 2 irregular series or 1 series, with 5-9 ± undifferentiated tepals; stamens in male flowers 4-8(-10)		(2)
+	Perianth in 2 series, with 4 or 5 sepals and 4 or 5 petals; stamens in male flowers 4 or 5		(14)
2 (1)	Gynoecium in female flowers 1(or 2)-carpelled and leaf rachises not winged but canaliculate with sides of channel rarely slightly spreading at apex of rachis.		32 Z. wutaiense
+	Gynoecium in female flowers 2-5-carpelled or if 1-carpelled then leaf rachises with wing to 6 mm wide on each side		(3)
3 (2)	Fruit follicles stipitate		(4)
+	Fruit follicles not stipitate		(6)
4 (3)	Leaflet blades 0.7-1.3 cm wide.		41 Z. stipitatum
+	Leaflet blades usually at least 1.5 cm wide		(5)
5 (4)	Leaves 3-5(-11)-foliolate; follicles apically shortly beaked.		29 Z. dimorphophyllum
+	Leaves 5-15-foliolate; follicles not apically beaked.		40 Z. simulans
6 (3)	Leaf rachises usually conspicuously winged		(7)
+	Leaf rachises not conspicuously winged but sometimes with a distinct margin		(8)
7 (6)	Wings of leaf rachis extending to as much as 3 mm on each side; secondary veins of leaflet blades evident, 10-28 on each side of midvein; anthers in male flowers reddish purple prior to anthesis; gynoecium in female flowers 2-5-carpelled.		30 Z. acanthopodium
+	Wings of leaf rachis extending to as much as 6 mm on each side; secondary veins of leaflet blades generally faint especially adaxially, 7-15 on each side of midvein; anthers in male flowers yellow prior to anthesis; gynoecium in female flowers 1-3-carpelled.		31 Z. armatum
8 (6)	Fruit follicles pubescent; branchlets covered with setiform prickles and compressed pseudostipular prickles decurrent along branchlet and forming a wing joining them between nodes.		39 Z. pteracanthum
+	Fruit follicles glabrous; branchlets without compressed pseudostipular prickles joined by a wing		(9)
9 (8)	Leaflet blades to 3 × 1.5 cm		(10)
+	Leaflet blades usually larger than 3 × 1.5 cm		(11)
10 (9)	Leaflet blades reddish brown to blackish brown when dry.		37 Z. piasezkii
+	Leaflet blades grayish green to yellowish green when dry.		38 Z. pilosulum
11 (9)	Leaf near inflorescence on fertile branchlet 3-foliolate, with terminal leaflet 4-6 cm wide.		36 Z. motuoense
+	Leaf near inflorescence on fertile branchlet more than 5-foliolate, with terminal leaflet less than 3.5 cm wide		(12)
12 (11)	Leaf rachises terete, glabrous.		35 Z. austrosinense
+	Leaf rachises with a distinct margin or pubescent		(13)
13 (12)	Leaflet blades abaxially flocculent along midvein and adaxially glabrous or both surfaces pubescent.		33 Z. bungeanum
+	Leaflet blades abaxially glabrous and adaxially hirsutulous to sparsely puberulent.		34 Z. undulatifolium
14 (1)	Flowers 5-merous; trees or rarely shrubs		(15)
+	Flowers 4-merous; woody climbers, shrubs, or rarely trees		(22)
15 (14)	Shrubs; leaflet blades rarely wider than 2 cm, adaxially with trichomes and abaxially glabrous.		28 Z. schinifolium
+	Trees; leaflet blades wider than 2 cm, adaxially glabrous or both surfaces with trichomes		(16)
16 (15)	Fertile branchlets unarmed, with small pith; leaf rachises winged		(17)
+	Fertile branchlets armed, with large pith; leaf rachises not winged		(18)
17 (16)	Gynoecium in female flowers 2(or 3)-carpelled; leaflet blades asymmetric, oblique at base.		23 Z. avicennae
+	Gynoecium in female flowers 3(or 4)-carpelled; leaflet blades at base rounded to broadly cuneate, symmetric or asymmetric.		24 Z. micranthum
18 (16)	Leaflet blades glabrous		(19)
+	Leaflet blades abaxially and/or adaxially with trichomes		(20)
19 (18)	Leaflet blades dark green to light yellowish green when dry, abaxially glaucous.		25 Z. ailanthoides
+	Leaflet blades reddish brown to blackish brown, abaxially not glaucous.		26 Z. myriacanthum
20 (18)	Leaflet blades abaxially and adaxially with trichomes.		26 Z. myriacanthum
+	Leaflet blades abaxially with trichomes, otherwise glabrous		(21)
21 (20)	Leaflet blades abaxially with a soft woolly villous indumentum.		27 Z. molle
+	Leaflet blades abaxially pubescent.		25 Z. ailanthoides
22 (14)	Gynoecium in female flowers 2- or 3-carpelled and styles usually recurved; follicles stipitate.		29 Z. dimorphophyllum
+	Gynoecium in female flowers 1-carpelled or if 2-4-carpelled then styles usually erect to spreading-ascending; follicles not stipitate		(23)
23 (22)	Inflorescences terminal, cymose-corymbiform; pedicel at least 1 cm in fruit and purplish red like follicles		(24)
+	Inflorescences axillary and terminal, thyrsiform; pedicel rarely to 1 cm in fruit and not purplish red		(26)
24 (23)	Fruit pedicel 1-1.5 cm, ca. 1 mm wide; leaflet blades with numerous oil glands, midvein adaxially impressed and puberulent, margin of blade serrulate.		20 Z. oxyphyllum
+	Fruit pedicel 1.5-4.5 cm, less than 1 mm wide; leaflet blades with inconspicuous oil glands, midvein adaxially ridged, plane, or impressed, margin of blade crenulate or entire toward base		(25)
25 (24)	Midvein on adaxial surface of leaflet blades ridged or plane toward apex, petiolules pubescent adaxially.		21 Z. stenophyllum
+	Midvein on adaxial surface of leaflet blades impressed, petiolules glabrous.		22 Z. esquirolii
26 (23)	Fruit follicles with prickles and/or trichomes		(27)
+	Fruit follicles with neither prickles nor trichomes		(29)
27 (26)	Fruit follicles with prickles and trichomes.		19 Z. echinocarpum
+	Fruit follicles with trichomes, without prickles		(28)
28 (27)	Leaflets opposite; leaflet blades 7-19 × 5-8 cm.		17 Z. collinsiae
+	Leaflets alternate to opposite; leaflet blades 6-8 × 2.5-3.5 cm.		18 Z. liboense
29 (26)	Fruit follicles 1-1.5 cm; outer part of pericarp (exocarp and mesocarp) wider than endocarp.		16 Z. dissitum
+	Fruit follicles to 0.9 cm; outer part of pericarp not wider than endocarp		(30)
30 (29)	Leaflets opposite		(31)
+	Leaflets alternate or partly opposite		(33)
31 (30)	Trees; leaflet blades asymmetric.		3 Z. integrifolium
+	Woody climbers or shrubs; leaflet blades symmetric		(32)
32 (31)	Leaflet blades abaxially without oil glands along secondary veins, apex retuse at tip; petiolules obsolete or to 5 mm.		1 Z. nitidum
+	Leaflet blades abaxially with oil glands along secondary veins, apex not retuse at tip; petiolules ca. 1 mm.		2 Z. xichouense
33 (30)	Leaflet blades abaxially, leaf rachises, and inflorescences tomentulose.		4 Z. tomentellum
+	Leaflet blades abaxially, leaf rachises, and inflorescences glabrous or puberulent		(34)
34 (33)	Leaves with numerous oil glands which project outward when dry		(35)
+	Leaves with few oil glands or oil glands inconspicuous		(38)
35 (34)	Fruit follicles not apically beaked; leaflet blade oil glands light yellow to brown when dry, pellucid.		5 Z. glomeratum
+	Fruit follicles usually apically beaked; leaflet blade oil glands brown or blades blackish brown when dry		(36)
36 (35)	Leaves 3- or 7(or 9)-foliolate; leaflet blades at least 5 cm, lustrous when dry.		6 Z. macranthum
+	Leaves 7-51-foliolate; leaflet blades rarely to 5 cm, dull when dry		(37)
37 (36)	Leaves 7-15-foliolate; leaflet blades symmetric or subsymmetric, midvein adaxially impressed.		7 Z. rhombifoliolatum
+	Leaves 17-51-foliolate; leaflet blades asymmetric, midvein adaxially plane to ridged.		13 Z. multijugum
38 (34)	Leaf rachises with straight prickles 5-10 mm.		8 Z. leiboicum
+	Leaf rachises unarmed or with curved prickles rarely to 5 mm		(39)
39 (38)	Fruit follicles 7-8 mm; margin of leaflet blades entire.		9 Z. laetum
+	Fruit follicles 5-6 mm; margin of leaflet blades crenate at least near apex or rarely entire		(40)
40 (39)	Pedicel of fruit and rachis of infructescences glabrous or sparsely puberulent.		10 Z. scandens
+	Pedicel of fruit and rachis of infructescences puberulent or pubescent		(41)
41 (40)	Leaflet blades abaxially pubescent at least on midvein toward base or secondary veins.		11 Z. kwangsiense
+	Leaflet blades abaxially glabrous		(42)
42 (41)	Fruit pedicel 7-10 mm; petiolules 4-10 mm, leaflet blade apices caudate.		12 Z. khasianum
+	Fruit pedicel rarely more than 5 mm; petiolules 1-4 mm, leaflet blade apices acute, shortly acuminate, or shortly caudate		(43)
43 (42)	Leaflet blades 2-5 × 0.7-2.5 cm, apex acute or shortly acuminate; inflorescences to 3 cm; innovations glaucous.		14 Z. calcicola
+	Leaflet blades 6-10 × 2.5-4 cm, apex shortly caudate; inflorescences to 26 cm; innovations not glaucous.		15 Z. yuanjiangense